Coal gasification slag-based aerogel porous material and application thereof

Abstract

The invention discloses a coal gasification slag-based aerogel porous material and application thereof, and belongs to the field of compounds of non-metallic elements. The preparation method comprises the following steps: by taking regional bulk coal-based solid waste-coal gasification slag and a self-gelling natural polymer material as raw materials, pretreating the coal gasification slag to remove heavy metal ions, then preparing dispersion liquid from the coal gasification slag and a self-gelling natural polymer material solution, and carrying out first freeze drying to obtain a solidified material; then, soaking by using a cross-linking agent to form cross-linked aerogel, fully soaking the cross-linked aerogel by using a tert-butyl alcohol solution, and performing freeze drying for the second time to obtain the coal gasification slag-based aerogel porous material. The prepared composite aerogel has super-hydrophilicity, excellent water absorption and water retention properties and excellent photo-thermal conversion performance. Due to the characteristics, the composite aerogel can be used as a soil water-retaining agent or a soil conditioner; or is used as an interface evaporation material for treating high-salinity wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of non-metallic element compounds, in particular to a coal gasification slag-based aerogel porous material and its application. BACKGROUND

[0002] The coal chemical industry will produce a large amount of solid coal gasification slag. At present, due to the low comprehensive utilization rate of coal gasification slag and high disposal cost, its large-scale and resource-based utilization still faces practical obstacles, and most of them are still treated by stacking and landfill. This traditional disposal method has significant environmental risks, for example, under the action of acid rain, various heavy metal ions (such as Cr, Pb, Ni, As, Cd, etc.) in the stacked coal gasification slag are easily dissolved and then migrate and pollute the surrounding soil and water, posing a potential threat to the regional ecological environment. Therefore, in the process of realizing the clean utilization of coal resources, it is urgent to accelerate the resource-based utilization of coal gasification slag and reduce its harm to the environment.

[0003] Aerogel is a kind of porous material with three-dimensional network structure, which has the characteristics of low density, high porosity, high specific surface area, low thermal conductivity, etc. The unique porous structure makes it have a broad application prospect in the fields of thermal insulation, adsorption separation, photoelectric catalysis, sound absorption and insulation, and energy storage conversion. Preparing coal gasification slag into aerogel advanced functional materials is expected to open up a new path for the high-value resource utilization of this solid waste.

[0004] The prior art, Chinese patent (CN119706819A) discloses a method for preparing aerogel by using high-carbon components of coal gasification fine slag, which comprises the following steps: separating the high-carbon components of coal gasification fine slag into light carbon and heavy carbon by isodensity gradient centrifugation or ultrasonic separation; synthesizing carbon aerogel by chemical activation of the light carbon after acid leaching and impurity removal; and obtaining graphene aerogel by "alkali activation reduction-acid washing-normal pressure drying" after obtaining graphene by stripping and intercalation of the heavy carbon. The production process needs to go through operations such as isodensity gradient centrifugation or ultrasonic separation, high-temperature chemical activation, etc., and the process needs to be carried out under strong acid and strong base reaction conditions, which not only has a complicated process and harsh conditions, but also leads to a high comprehensive cost of the product. SUMMARY

[0005] The purpose of the present application is to provide a coal gasification slag-based aerogel porous material and its application, which utilizes coal gasification slag to prepare aerogel by a new method. The technical scheme adopted by the present application is as follows.

[0006] In a first aspect, the present application provides a coal gasification slag-based aerogel porous material, and a preparation method thereof, which comprises: coal gasification slag pretreatment: grinding the coal gasification slag, soaking the coal gasification slag in nitric acid solution for modification, washing the coal gasification slag with water, and drying the coal gasification slag to obtain pretreated coal gasification slag; dispersing the pretreated coal gasification slag into a solution of a natural polymer material capable of self-gelation to prepare a dispersion liquid, wherein the natural polymer material contains at least one of carboxyl, hydroxyl, and aldehyde groups; subjecting the dispersion liquid to first freeze-drying to obtain a solidified material; soaking the solidified material in a crosslinking agent solution, and washing the solidified material with water to obtain a crosslinked aerogel; soaking the crosslinked aerogel in a tert-butyl alcohol solution, and subjecting the crosslinked aerogel to second freeze-drying to obtain the coal gasification slag-based aerogel porous material.

[0007] Further, the coal gasification slag is a coal gasification coarse slag or a coal gasification fine slag; the coal gasification slag is sieved after grinding, and the coal gasification slag sieved by a 50-200 mesh sieve is selected; the nitric acid solution used for soaking and modification is a 3-6 mol / L nitric acid solution, the soaking time is 3-6 h, and the soaking temperature is 60-120 ℃; the drying temperature during the pretreatment of the coal gasification slag is 60-100 ℃, and the drying time is 3-5 h.

[0008] Further, the natural polymer material capable of self-gelation is chitosan; the chitosan is mixed with an acetic acid solution to prepare the solution of the natural polymer material capable of self-gelation.

[0009] Further, the natural polymer material capable of self-gelation is any one of pectin and starch, and the natural polymer material capable of self-gelation is mixed with water to prepare the solution of the natural polymer material capable of self-gelation.

[0010] Further, the mixing mass ratio of the pretreated coal gasification slag to the solution of the natural polymer material is 1: (10-90).

[0011] Further, the first freeze-drying of the dispersion liquid is performed under the following conditions: the cold trap temperature is -40 to -60 ℃, the freeze-drying time is 48-72 h, and the vacuum degree is 30-100 Pa.

[0012] Further, the crosslinking agent is a glutaraldehyde solution, the volume fraction of the crosslinking agent is 1.5-2.5%, the soaking time of the crosslinking agent is 24-48 h, and then the crosslinked aerogel is soaked in deionized water to remove the excess crosslinking agent until the conductivity of the soaking liquid of the crosslinked aerogel is 1-10 μS / cm; the crosslinked aerogel is soaked in a tert-butyl alcohol solution, and then subjected to second freeze-drying, wherein the cold trap temperature is -40 to -60 ℃, the freeze-drying time is 48-72 h, and the vacuum degree is 30-100 Pa, to obtain the coal gasification slag-based aerogel porous material.

[0013] In a second aspect, the present application provides a coal gasification slag-based aerogel porous material, and a preparation method thereof, which comprises: coal gasification slag pretreatment: grinding the coal gasification slag, soaking the coal gasification slag in nitric acid for modification, washing the coal gasification slag with water, and drying the coal gasification slag to obtain pretreated coal gasification slag; dispersing the pretreated coal gasification slag into a sodium alginate solution to prepare a dispersion liquid; performing first freeze-drying on the dispersion liquid to obtain a solidified material; soaking the solidified material in a calcium chloride solution, washing the solidified material with water to obtain a cross-linked aerogel; soaking the cross-linked aerogel in a tert-butyl alcohol solution, and performing second freeze-drying to obtain the coal gasification slag-based aerogel porous material.

[0014] In a third aspect, the present application provides an application of the coal gasification slag-based aerogel porous material, which is used as a soil water-retaining agent or a soil conditioner.

[0015] In a fourth aspect, the present application provides an application of the coal gasification slag-based aerogel porous material, which is used as an interfacial evaporation material for treating high-salinity wastewater.

[0016] The composite aerogel prepared by the present application has superhydrophilicity, excellent water absorption and retention, and excellent light-heat conversion performance. These characteristics enable the composite aerogel to be applied in various fields. For example, in the field of agriculture, the material can quickly absorb soil moisture and continuously transport water to crop roots, providing stable water support for crop growth and alleviating the problem of soil water shortage in drought areas to a certain extent. In the field of high-salinity wastewater desalination, the material can continuously absorb water from wastewater and efficiently transport it to the evaporation interface, and the excellent light-heat conversion capability ensures the evaporation rate, thereby realizing green desalination of high-salinity wastewater and recovery of salt resources. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 shows a scanning electron microscope image of the coal gasification slag after step one and step two in Example 1 of the present application.

[0018] Figure 2 FIG. 2 shows an X-ray diffraction analysis graph of the coal gasification slag after step one and step two in Example 1 of the present application.

[0019] Figure 3 FIG. 3 shows an appearance graph of the composite aerogel prepared in Example 1 of the present application.

[0020] Figure 4 FIG. 4 shows a scanning electron microscope image of the composite aerogel prepared in Example 1 of the present application; Figure 4 a is a scanning electron microscope image of the composite aerogel under a 500 μm scale, Figure 4 b is a scanning electron microscope image of the composite aerogel under a 100 μm scale, Figure 4 c is a scanning electron microscope image of the composite aerogel under a 10 μm scale.

[0021] Figure 5 Figure 1 shows the UV-Vis-NIR absorption spectrum of the composite aerogel prepared in Example 1 of the present application.

[0022] Figure 6 Figure 2 shows the pore size distribution curve of the composite aerogel prepared in Example 1 of the present application.

[0023] Figure 7 Figure 3 shows the differential mesopore size distribution curve of the composite aerogel prepared in Example 1 of the present application, measured by nitrogen adsorption-desorption experiment.

[0024] Figure 8 Figure 4 shows the contact angle test diagram of the composite aerogel prepared in Example 1 of the present application and water droplets.

[0025] Figure 9 Figure 5 shows the water absorption saturation curve of the composite aerogel prepared in Example 1 of the present application, measured by water absorption test.

[0026] Figure 10 Figure 6 shows the water loss rate curve of the composite aerogel prepared in Example 1 of the present application after saturated adsorption under centrifugal action.

[0027] Figure 11 Figure 7 shows the structure diagram of an interface evaporation test device according to the present application.

[0028] Figure 12 Figure 8 shows the evaporation efficiency curve of the composite aerogel obtained by evaporation efficiency test according to the present application.

[0029] Figure 13 Figure 9 shows the scanning electron microscope image of the coal gasification fine slag treated by Step 1 and Step 2 in Example 7 of the present application.

[0030] Figure 14 Figure 10 shows the X-ray diffraction analysis diagram of the coal gasification coarse slag treated by Step 1 and Step 2 in Example 7 of the present application.

[0031] Figure 15 Figure 11 shows the product diagrams of the composite aerogels prepared by using glutaraldehyde solutions with volume fractions of 1.5%, 2.0% and 3.5%, respectively; wherein, Figure 15 a is the composite aerogel material prepared by using a glutaraldehyde solution with a volume fraction of 1.5%; Figure 15 b is the composite aerogel material prepared by using a glutaraldehyde solution with a volume fraction of 2.0%; Figure 15 c is the composite aerogel material prepared by using a glutaraldehyde solution with a volume fraction of 2.5%.

[0032] Legend of reference signs: container 1, polyethylene foam 2, aerogel 3, weighing device 4, light-transmitting shell cover 5, xenon lamp 6. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0034] The source and characteristic indexes of the main raw materials in the present application are shown in Table 1 below.

[0035] Table 1, the source and characteristic indexes of the main raw materials in the present application

[0036] Embodiment 1, the present embodiment provides a coal gasification coarse slag-chitosan aerogel porous material, which is prepared by the following method.

[0037] Step one, use a ball mill to grind and treat the coal gasification coarse slag. In the present embodiment, the power of the ball mill is 750 W, and the rotating speed is adjusted to 500 rap / min; add the coal gasification coarse slag, and start the ball mill to grind for 60 min; then use a 100-mesh sieve to screen, and obtain the 100-mesh coal gasification coarse slag.

[0038] The content statistical table of heavy metal oxides in the screened coal gasification coarse slag is shown in Table 2 below.

[0039] Table 2, the content statistical table of heavy metal oxides in the screened coal gasification coarse slag in step one of embodiment 1

[0040] Step two, add 6 mol / L nitric acid solution in the acid leaching tank, start the electric heater until the temperature of the temperature controller reaches and stabilizes to 80 ℃, and then add the above screened coal gasification coarse slag to soak for 4 h; then filter the leaching liquid and the solid insoluble substance, and wash the solid insoluble substance with deionized water for multiple times until its pH value is neutral. After drying the washed solid in an oven at a temperature of 80 ℃ for 4 h, take it out.

[0041] The function of step two in the present embodiment is as follows: through acid leaching treatment, the acid-soluble heavy metal ions in the coal gasification slag can react with the acid to generate soluble nitrate and enter the leaching liquid, realizing efficient removal of heavy metal ions, and ensuring that the coal gasification slag-based aerogel material prepared subsequently as a soil water-retaining agent, a soil conditioner or an interfacial evaporation material will not cause heavy metal pollution to the soil ecology and water environment.

[0042] The content statistical table of heavy metal oxides in the coal gasification coarse slag after acid leaching treatment is shown in Table 3 below.

[0043] Table 3, Example 1 Step two acid leaching after the content of heavy metal oxides in coal gasification coarse slag statistics table

[0044] As Figure 1 shown is the coal gasification coarse slag after step one, step two of the present application embodiment 1 scanning electron microscope image. As can be seen from the figure, the coal gasification coarse slag surface is layered structure, the structure provides exclusive attachment site for chitosan solution, and then avoid chitosan solution because of free agglomeration makes composite aerogel material form dense non-porous block structure.

[0045] Figure 2 As shown is the coal gasification coarse slag after step one, step two of the present application embodiment 1 X-ray diffraction analysis chart. As can be seen from the figure, the characteristic diffraction peak of about 20 ° is highly consistent with the carbon phase standard peak, and the dense diffraction peak in the interval of 30 °-70 ° matches the standard diffraction peak of silicon dioxide, which shows that after the treatment of steps one and two of the present application, the coarse slag still retains the rigid skeleton component of silicon dioxide and the carbon component. Silicon dioxide as a rigid component can make up for the defect of pure chitosan aerogel that is easy to shrink and collapse; and the carbon component can significantly improve the technical defect of pure chitosan aerogel that the light-heat conversion efficiency is insufficient, and is the core functional component for realizing the target light-heat function of composite aerogel.

[0046] Step three, use a measuring cylinder to take 49 mL of deionized water in a beaker, and add 1 mL of glacial acetic acid, stir to get a volume fraction of 2% glacial acetic acid solution. Add 1 g of chitosan in the beaker, stir to dissolve, then use the volume fraction of 2% glacial acetic acid solution to constant volume to 100 mL, and stir the constant volume solution at room temperature with a high speed homogenizer at a speed of 7000 rap / min for 3.2 h to get a 10 g / L chitosan solution with a viscosity of 15000 mPa·s.

[0047] Viscosity is a key factor to determine the stability of aerogel microstructure and process operability. The viscosity of natural polymer material solution with different concentrations is significantly different. In order to realize the stable suspension of coal gasification slag in natural polymer solution and avoid particle sedimentation and accumulation, the viscosity of natural polymer material solution needs to be controlled. Specifically, in the present application, when the viscosity is less than 30 mPa·s, the suspension carrying capacity of the solution is insufficient, and the sample will shrink and collapse due to insufficient structural support during the subsequent freeze-drying process. When the viscosity is greater than 20000 mPa·s, the fluidity of the solution will deteriorate sharply, and the coal gasification slag particles will be difficult to disperse uniformly, and will easily form large agglomerates, so that a uniform suspension cannot be obtained. Therefore, in the present application, the viscosity of the chitosan solution is preferably 30 mPa·s-20000 mPa·s.

[0048] Step 4: Weigh 5.0 g of the chitosan solution prepared in Step 3 into a beaker, add 0.1 g of the coal gasification coarse slag treated in Step 2, and stir thoroughly at room temperature to obtain a coal gasification coarse slag-chitosan suspension. Freeze-dry the above suspension at a cold trap temperature of -50 ℃ and a vacuum degree of 30 Pa for 72 h to obtain a coal gasification coarse slag-based solid.

[0049] Step 5: Use a pipette to measure 2 mL of glutaraldehyde into a 100 mL volumetric flask, add 90 mL of deionized water to the volumetric flask, gently shake the volumetric flask to mix the glutaraldehyde and deionized water evenly, and then make up to 100 mL with deionized water to obtain a 2% glutaraldehyde solution.

[0050] Step 6: Completely immerse the coal gasification coarse slag-based solid prepared in Step 4 in the glutaraldehyde solution prepared in Step 5 for 24 h. Then, soak it repeatedly with deionized water to remove excess crosslinking agent until the conductivity of the soaking solution is 8 μS / cm, thus obtaining crosslinked coal gasification coarse slag-chitosan aerogel.

[0051] The conductivity value measured in the soaking solution is an important indicator for measuring the amount of residual crosslinking agent, because the conductivity of deionized water is between 1 and 10 μS / cm. When the conductivity of the soaking solution is within this range, it indicates that there is no residual crosslinking agent.

[0052] Step 7: Measure 90 mL of deionized water and 60 mL of tert-butanol into a beaker using a graduated cylinder, and stir at room temperature to obtain a tert-butanol solution. Completely immerse the cross-linked coal gasification slag-chitosan aerogel prepared in Step 6 into the prepared tert-butanol solution and soak for 4 h. Since the tert-butanol solution is volatile and needs to gradually diffuse from the outside of the aerogel to the inside, to ensure sufficient solvent replacement, the tert-butanol solution was prepared three times and the soaking was repeated three times in this embodiment. Freeze-dry the soaked aerogel at a cold trap temperature of -50 °C and a vacuum degree of 32 Pa for 72 h to obtain the coal gasification slag-chitosan composite aerogel.

[0053] like Figure 3 The image shown is an appearance diagram of the composite aerogel prepared in Example 1 of this invention. The composite aerogel prepared in this example is black and cylindrical in shape. Measurements show its diameter d = 1.5 cm and height h = 3 cm. Its apparent volume V can be calculated. b =5.30 cm 3 The mass m of the aerogel was weighed using an electronic analytical balance. b =0.1543 g.

[0054] like Figure 4 The image shown is a scanning electron microscope (SEM) image of the composite aerogel prepared in Example 1 of this invention.Figure 4 As shown in Figure a, at a scale of 500 μm, the composite aerogel of this invention clearly exhibits a lamellar structure with numerous visible pores. Figure 4 As shown in b, under a 100 μm scale, the holes can be seen to be interconnected; as Figure 4 As shown in c, at a scale of 10 μm, a large number of uniformly sized coal gasification slag particles embedded in chitosan can be clearly seen on the layered structure.

[0055] Detection using a UV-Vis-NIR spectrometer revealed that the composite aerogel exhibited an absorbance of approximately 94% in the 200-2500 nm wavelength range, demonstrating extremely strong light absorption capabilities. Figure 5 The image shows the ultraviolet-visible-near-infrared absorption spectrum of the composite aerogel prepared in Example 1 of this invention.

[0056] This invention uses a fully automated mercury porosimeter to detect the pore size distribution of the composite aerogel prepared in Example 1 of this invention, such as... Figure 6 The figure shows the pore size distribution curve of the composite aerogel prepared in Example 1 of this invention. As can be seen from the figure, the main pore size of the composite aerogel is concentrated around 100 μm, with pore sizes smaller than 10 μm and close to 1000 μm accounting for a very small percentage. Meanwhile, the test results show that the macropore (pore size greater than 50 nm) porosity of the composite aerogel is 95.36%.

[0057] The average pore size (pore size between 2-50 nm) of the composite aerogel, measured using a fully automated physical adsorption instrument, is 10 nm. Figure 7 The figure shows the differential curve of the mesopore size distribution of the composite aerogel prepared in Example 1 of this invention, determined by nitrogen adsorption-desorption experiment. As can be seen from the figure, the mesopore size of the composite aerogel is mainly concentrated around 10 nm, with some pores around 17 nm, and a small number of pores smaller than 5 nm and larger than 20 nm.

[0058] like Figure 8 The image shows a test diagram of the contact angle between the surface of the composite aerogel prepared in Example 1 of this invention and a water droplet. Detected by a video optical contact angle meter, the contact angle between the composite aerogel of this invention and water in air is close to 0°, and the water droplet spreads and penetrates the material surface upon contact.

[0059] This invention conducts a water absorption test on the composite aerogel prepared in Example 1. The test procedure is as follows: The sample is completely immersed in deionized water, and a stopwatch is started simultaneously. The spreading of water droplets on the material surface and the internal water absorption process are observed. When the sample mass no longer increases, the time taken is recorded, which is the saturation adsorption time. Figure 9The water absorption saturation curve of the composite aerogel prepared in Example 1 is shown. The saturated adsorption time of the material in water is 0.95 s, and the average saturated adsorption specific gravity is 28.5 g / g.

[0060] The water retention capacity of the composite aerogel prepared in Example 1 was tested. The test process is as follows: the composite aerogel after water absorption test was centrifuged in a high-speed centrifuge with a rotation speed of 10000 rap / min. As shown in Figure 10 The water loss rate curve of the composite aerogel prepared in Example 1 under the action of centrifugation after saturated adsorption is shown. After saturated adsorption, the water loss rate of the composite aerogel is less than 44% after 10 min of centrifugation.

[0061] Further, the sample after water absorption and water retention test was placed in an oven for drying, and then the above water absorption and water retention test was repeated. The test results show that the water loss rate of the sample is 43.1% in the first repeated test, and after 5 times of continuous repeated test, the water loss rate is stably reduced to 38.7%, and when the repeated test is continued to 8 times, the water loss rate still maintains at about 38.1%, without obvious change.

[0062] The evaporation efficiency of the composite aerogel prepared in Example 1 was tested. The test process is as follows: as shown in Figure 11 The structure of the interface evaporation test device of the present application is shown. The device includes a container 1, and 3.5 wt% salt water is added to the container 1; polyethylene foam 2 is used as a support, and a through hole is opened in the center of the polyethylene foam 2, and the aerogel 3 prepared by the present application is embedded in the through hole. The polyethylene foam 2 is placed in a floating state on the surface of the salt water, and the lower surface of the aerogel 3 contacts the salt water. The container 1 is placed on a weighing device 4, such as an electronic scale, which is used to measure the mass change of the container 1. Then the container 1 and the weighing device 4 are covered with a light-transmitting shell 5 to form a closed space inside. The light-transmitting shell 5 can be made of pet material, and the full wavelength of sunlight can pass through this material. The light-transmitting shell 5 in the present application is in the shape of a rectangular parallelepiped, with an opening at the bottom and an inclined top surface; the inclined surface can guide the condensed water to one side to avoid the condensed water falling back into the container 1; if the condensed water falls back into the container 1, it will cause inaccurate evaporation data. The above complete equipment is installed directly below the xenon lamp 6 of the xenon lamp light source system. The model of the xenon lamp light source system is CEL-HXF300-T3. The xenon lamp light source system simulates sunlight.

[0063] During the test, under the simulated sunlight (1 sun irradiation), the steam generated in the evaporation test device condenses into desalination water on the surface of the light-transmitting shell. The mass of the container decreases continuously, and the mass change value of the container is recorded with time. As shown in Figure 12 The evaporation efficiency curve of the composite aerogel prepared in Example 1 is shown.

[0064] The evaporation efficiency of the composite aerogel of the present application is calculated according to the following formula 1.

[0065] Evaporation efficiency calculation formula 1:

[0066] In formula 1, is the evaporation mass increment (kg) in a specific time, A is the evaporation area (m 2 ), is the evaporation time interval (s). In the present application, = 1 h, = 0.371 g, A = 1.767 cm 2 calculated, U = 2.1 kg·m -2 ·h -1 , so its evaporation rate is 2.1 kg·m -2 ·h -1 .

[0067] In summary: the composite aerogel prepared in Example 1 of the present application has superhydrophilicity, excellent water absorption and water retention, and excellent light-heat conversion performance. These characteristics enable the composite aerogel of the present application to be applied in various fields. For example, in the field of agriculture, the material can quickly absorb soil moisture and continuously transport water to the roots of crops, providing stable water support for crop growth and to some extent alleviating the problem of soil water shortage in drought areas. In the field of high-salt wastewater desalination, the material can continuously absorb water from wastewater and efficiently transport it to the evaporation interface, and its excellent light-heat conversion capability ensures the evaporation rate, thereby realizing green desalination of high-salt wastewater and recovery of salt resources.

[0068] Example 2, the present example provides a coal gasification coarse slag-chitosan aerogel porous material, which is prepared by the following method.

[0069] Step one, use a ball mill to grind the coal gasification coarse slag. In the present example, the power of the ball mill is 750 W, and the rotating speed is adjusted to 800 rap / min; add the coal gasification coarse slag, and start the ball mill to grind for 120 min; then use a 200-mesh sieve to screen, and obtain the coal gasification coarse slag with a mesh size of 200.

[0070] Step two, add 6 mol / L nitric acid solution in the acid leaching tank, start the electric heater until the temperature of the temperature controller reaches and stabilizes at 120 ℃, add the coal gasification coarse slag screened above and soak for 6 h; then filter the leaching liquid and the solid insoluble substance, and wash the solid insoluble substance with deionized water for several times until its pH value is neutral. After drying the washed solid in an oven at a temperature of 100 ℃ for 5 h, take it out.

[0071] Step three, 49 mL of deionized water was measured in a measuring cylinder and 1 mL of glacial acetic acid was added in a beaker, and the glacial acetic acid solution with a volume fraction of 2% was obtained by stirring. 1 g of chitosan was added in the beaker, and after stirring and dissolving, the volume was adjusted to 100 mL with the glacial acetic acid solution with a volume fraction of 2%, and the solution after volume adjustment was stirred at room temperature for 5 h using a high-speed homogenizer with a rotation speed of 12000 rap / min. A chitosan solution with a concentration of 10 g / L was obtained, and the viscosity was 15000 mPa·s.

[0072] Step four, 9.0 g of chitosan solution prepared in step three was weighed in a beaker, and 0.1 g of coal gasification coarse residue treated in step two was added, and the mixture was fully stirred and dispersed at room temperature to obtain a coal gasification coarse residue-chitosan suspension. The suspension was freeze-dried under the conditions of a cold trap temperature of minus 60 ℃ and a vacuum degree of 100 Pa for 72 h to obtain a coal gasification coarse residue-based solid.

[0073] Step five, 2 mL of glutaraldehyde was measured in a 100 mL volumetric flask using a pipette, 90 mL of deionized water was added to the volumetric flask, and the volumetric flask was gently shaken to initially mix the glutaraldehyde and deionized water uniformly, and then deionized water was added to the volumetric flask to a volume of 100 mL to obtain a glutaraldehyde solution with a volume fraction of 2%.

[0074] Step six, the coal gasification coarse residue-based solid prepared in step four was completely immersed in the glutaraldehyde solution prepared in step five, and soaked for 48 h, and then soaked in deionized water multiple times to remove excess cross-linking agent until the conductivity of the soaking liquid was 1 μS / cm, and a cross-linked coal gasification coarse residue-chitosan aerogel was obtained.

[0075] Step seven, 90 mL of deionized water and 60 mL of tert-butyl alcohol were measured in a beaker using a measuring cylinder, and the mixture was stirred at room temperature to obtain a tert-butyl alcohol solution; the cross-linked coal gasification coarse residue-chitosan aerogel prepared in step six was completely immersed in the prepared tert-butyl alcohol solution, and soaked for 4 h; the tert-butyl alcohol solution was prepared for 3 times, and the soaking was repeated for 3 times. The soaked aerogel was freeze-dried under the conditions of a cold trap temperature of minus 60 ℃ and a vacuum degree of 100 Pa for 72 h to obtain a coal gasification coarse residue-chitosan composite aerogel.

[0076] The composite aerogel prepared in this example has a contact angle with water close to 0° in air, and water droplets spread and penetrate the material surface instantly. In water, the material has a saturation adsorption time of 1.71 s and an average saturation adsorption specific gravity of 21.2 g / g. After centrifugation in a high-speed centrifuge at 10,000 rap / min for 10 min, the water loss rate is less than 53.7%. Nitrogen adsorption-desorption experiments show that the average mesopore diameter of the material is 10 nm, and mercury intrusion experiments show that the macropore porosity is 92.45%, and the evaporation efficiency is 1.9 kg·m -2 ·h -1 , and the absorbance of the substance in the wavelength range of 200-2500 nm is about 88%, showing a very strong light absorption capacity.

[0077] Example 3, this example provides a coal gasification coarse slag-chitosan aerogel porous material, which is prepared by the following method.

[0078] Step one, use a ball mill to grind the coal gasification coarse slag. In this example, the power of the ball mill is 750 W, and the speed is adjusted to 300 rap / min; add the coal gasification coarse slag, and start the ball mill to grind for 30 min; then use a 50-mesh sieve to screen, and obtain a 50-mesh coal gasification coarse slag.

[0079] Step two, add 3 mol / L nitric acid solution to the acid leaching tank, start the electric heater, and control the temperature to reach and stabilize at 60 ℃. Add the above-mentioned screened coal gasification coarse slag and soak for 3 h. Then filter the leaching liquid and the solid insoluble substance, and wash the solid insoluble substance with deionized water several times until the pH value is neutral. After drying the washed solid in an oven at 60 ℃ for 3 h, take it out.

[0080] Step three, measure 49 mL of deionized water in a beaker, and add 1 mL of glacial acetic acid to obtain a 2% volume fraction of glacial acetic acid solution. Add 1 g of chitosan to the beaker, stir to dissolve, and then use the 2% volume fraction of glacial acetic acid solution to make up to 100 mL. Stir the solution at room temperature using a high-speed homogenizer at a speed of 4000 rap / min for 3 h to obtain a 10 g / L chitosan solution with a viscosity of 15000 mPa·s.

[0081] Step four, weigh 5.0 g of the chitosan solution prepared in step three, and add 0.5 g of the coal gasification coarse slag treated in step two. Stir and disperse thoroughly at room temperature to obtain a coal gasification coarse slag-chitosan suspension. Freeze-dry the suspension at a cold trap temperature of -40 ℃ and a vacuum degree of 30 Pa for 48 h to obtain a coal gasification coarse slag-based solid.

[0082] Step five, 2 mL glutaraldehyde was measured by a pipette into a 100 mL volumetric flask, 90 mL deionized water was added into the volumetric flask, the volumetric flask was gently shaken to mix the glutaraldehyde and deionized water initially uniformly, and then the deionized water was added to 100 mL to obtain a 2% glutaraldehyde solution by volume fraction.

[0083] Step six, the coal gasification coarse slag-based solid prepared in step four was completely immersed in the glutaraldehyde solution prepared in step five, soaked for 24 h, and then soaked in deionized water for multiple times to remove the excess cross-linking agent until the conductivity of the soaking liquid was 10 μS / cm, to obtain a cross-linked coal gasification coarse slag-chitosan aerogel.

[0084] Step seven, 90 mL deionized water and 60 mL tert-butyl alcohol were measured by a graduated cylinder into a beaker, stirred at room temperature to obtain a tert-butyl alcohol solution; the cross-linked coal gasification coarse slag-chitosan aerogel prepared in step six was completely immersed in the prepared tert-butyl alcohol solution, soaked for 4 h; the tert-butyl alcohol solution was prepared for 3 times and the soaking was repeated for 3 times. The soaked aerogel was freeze-dried at a cold trap temperature of minus 40℃ and a vacuum degree of 30 Pa for 48 h to obtain a coal gasification coarse slag-chitosan composite aerogel.

[0085] The composite aerogel prepared in this example has a contact angle with water close to 0° in air, and the water droplets spread and penetrate on the surface of the material instantly. In water, the saturated adsorption time of the material is 2.76 s, and the average saturated adsorption specific gravity is 15.2 g / g. After centrifugation in a high-speed centrifuge at a speed of 10000 rap / min for 10 min, the water loss rate is less than 63.7%. The average mesopore diameter of the material is 10 nm measured by nitrogen adsorption and desorption experiment, the macropore porosity is 83.63% measured by mercury intrusion experiment, the evaporation efficiency is 1.53 kg·m -2 ·h -1 , and the absorbance of the substance in the wavelength range of 200-2500 nm is about 95%, showing a strong light absorption capacity.

[0086] Example 4, which is based on example 1 and makes the following changes.

[0087] Step three, 90 mL deionized water was measured by a graduated cylinder, 1 g pectin was added, stirred to dissolve, and then deionized water was added to 100 mL. The solution after constant volume was stirred at 80 o C water bath heating for 3 h to obtain a 10 g / L pectin solution with a viscosity of 11 mPa·s.

[0088] The difference between this example and example 1 is mainly that pectin is used instead of chitosan in this example.

[0089] The coal gasification coarse slag-pectin composite aerogel prepared in this example has a contact angle with water close to 0° in air, and water droplets spread and penetrate the material surface instantaneously. In water, the saturated adsorption time of the material is 1.88 s, and the average saturated adsorption specific gravity is 19.5 g / g. After centrifugation in a high-speed centrifuge at a speed of 10,000 rap / min for 10 min, the water loss rate is less than 46%. Nitrogen adsorption-desorption experiments show that the average mesopore diameter of the material is 9 nm, mercury intrusion experiments show that the macropore porosity is 89.72%, and the evaporation efficiency is 1.5 kg·m -2 ·h -1 , and the absorbance of the substance in the wavelength range of 200-2500 nm is about 94%, showing extremely strong light absorption capacity.

[0090] Example 5, which is based on Example 1 with the following changes. Step three of Example 1 is replaced with the following.

[0091] Step three, 90 mL of deionized water is measured with a measuring cylinder, 1 g of corn starch is added, after stirring and dissolving, deionized water is added to 100 mL, and the solution after constant volume is stirred at room temperature using a high-speed homogenizer at a speed of 9000 rap / min for 3 h to obtain a 10 g / L corn starch solution with a viscosity of 3000 mPa·s.

[0092] The difference between this example and Example 1 is mainly that corn starch is used instead of chitosan in this example.

[0093] The coal gasification coarse slag-corn starch composite aerogel prepared in this example has a contact angle with water close to 0° in air, and water droplets spread and penetrate the material surface instantaneously. In water, the saturated adsorption time of the material is 2.20 s, and the average saturated adsorption specific gravity is 22.3 g / g. After centrifugation in a high-speed centrifuge at a speed of 10,000 rap / min for 10 min, the water loss rate is less than 56%. Nitrogen adsorption-desorption experiments show that the average mesopore diameter of the material is 6 nm, mercury intrusion experiments show that the macropore porosity is 92.95%, and the evaporation efficiency is 1.8 kg·m -2 ·h -1 , and the absorbance of the substance in the wavelength range of 200-2500 nm is about 94%, showing extremely strong light absorption capacity.

[0094] Example 6, which is based on Example 1 with the following changes. Step three and step five of Example 1 are replaced with the following.

[0095] Step three, 90 mL of deionized water was measured in a measuring cylinder into a beaker, 1 g of sodium alginate was added, after stirring and dissolving, deionized water was used to constant volume to 100 mL, the constant volume solution was stirred at room temperature for 3 h by using a high speed homogenizer with a rotating speed of 9000 rap / min, and a sodium alginate solution with a viscosity of 1580 mPa·s was obtained.

[0096] In step five, the crosslinking agent was replaced by 10 g / L of calcium chloride solution. The preparation method is as follows: 90 mL of deionized water was measured in a measuring cylinder into a beaker, and 1 g of anhydrous calcium chloride was added, stirred uniformly at room temperature, and deionized water was used to constant volume to 100 mL, to obtain 10 g / L of calcium chloride solution.

[0097] The difference between this embodiment and example 1 is mainly that sodium alginate is used instead of chitosan in this embodiment; and the crosslinking agent is replaced by calcium chloride solution.

[0098] The coal gasification coarse slag-sodium alginate composite aerogel prepared in this embodiment has a contact angle with water close to 0° in air, and water droplets spread and penetrate on the surface of the material in an instant. In water, the saturated adsorption time of the material is 2.55 s, and the average saturated adsorption specific gravity is 20.6 g / g. After centrifugation in a high-speed centrifuge with a rotating speed of 10000 rap / min for 10 min, the water loss rate is less than 50%. The average mesopore diameter of the material is 10 nm measured by nitrogen adsorption and desorption experiment, the macropore porosity is 91.85% measured by mercury intrusion experiment, the evaporation efficiency is 1.75 kg·m -2 ·h -1 , and the absorbance of the substance in the wavelength range of 200-2500 nm is about 94%, showing a strong light absorption capacity.

[0099] Example 7, this example is based on example 1 and makes the following changes.

[0100] Step one, use a ball mill to grind the coal gasification fine slag. In this embodiment, the power of the ball mill is set to 550 W, and the rotating speed is adjusted to 500 rap / min; add the coal gasification fine slag, and start the ball mill to grind for 60 min; then use a 100 mesh sieve to screen, and get the 100 mesh coal gasification fine slag.

[0101] The following table 4 is the content of heavy metal oxides in the coal gasification fine slag before acid leaching treatment.

[0102] Table 4, content statistics table of heavy metal oxides in coal gasification fine slag before acid leaching treatment in example 7

[0103] The content of heavy metal oxides in the coal gasification fine slag after acid leaching treatment is shown in Table 5.

[0104] Table 5: Content statistics of heavy metal oxides in the coal gasification fine slag after acid leaching treatment of Example 7

[0105] Figure 13 The scanning electron microscope image of the coal gasification fine slag after step one and step two treatment of Example 7 of the present application is shown. As can be seen from the figure, the surface of the coal gasification fine slag presents a porous honeycomb structure, which provides a structural basis for the loading of chitosan, thereby avoiding the dense accumulation of chitosan solution due to free agglomeration, and at the same time, reserving sufficient pore space and mass transfer channels for the subsequent composite aerogel material.

[0106] Figure 14 The X-ray diffraction analysis graph of the coal gasification fine slag after step one and step two treatment of Example 7 of the present application is shown. As can be seen from the figure, the characteristic diffraction peak around 20° is highly matched with the standard peak of carbon, and the dense diffraction peak in the interval of 30°-70° is consistent with the standard diffraction peak of silicon dioxide, indicating that after the treatment of steps one and two of the present application, the fine slag still retains the rigid skeleton component of silicon dioxide and the carbonaceous component. Silicon dioxide as a rigid component can enhance the stability of the structure of the composite system and avoid the collapse of the functional material during the molding process; the carbonaceous component can endow the material with good light-heat conversion ability and ensure that the material has excellent evaporation performance. The difference between this embodiment and Example 1 is mainly that the coal gasification fine slag is used to replace the coal gasification coarse slag in this embodiment.

[0107] The coal gasification fine slag-chitosan composite aerogel prepared in this embodiment has a contact angle with water close to 0° in air, and the water droplets spread and penetrate the material surface instantaneously. In water, the saturated adsorption time of the material is 1.32 s, and the average saturated adsorption specific gravity is 26.3 g / g. After centrifugation in a high-speed centrifuge with a rotation speed of 10000 rap / min for 10 min, the water loss rate is less than 48%. The nitrogen adsorption-desorption experiment shows that the average pore size of the material is 8 nm, the mercury intrusion experiment shows that the macropore porosity is 91.43%, and the evaporation efficiency is 1.9 kg·m -2 ·h -1 , and the absorbance of the substance in the wavelength range of 200-2500 nm is about 94%, showing a very strong light absorption ability.

[0108] The present application further studies the influence of the amount of coal gasification coarse slag and chitosan solution in step four of Example 1 on the final product of the present application; the research process is as follows.

[0109] The ratio of the coal gasification coarse slag and the chitosan solution in Example 1 is 1:50; on the basis of Example 1, the ratio of the coal gasification coarse slag and the chitosan solution is changed to 1:10, 1:30, 1:70 and 1:90 respectively; other conditions remain unchanged. The performance indexes of the prepared composite aerogel are detected, and the results are shown in Table 6.

[0110] Table 6, Effect of different mass ratios of coal gasification coarse slag and chitosan solution on the performance of composite aerogel

[0111] The research shows that the different mass ratios of the coal gasification coarse slag and the chitosan solution have an important influence on the performance of the final product of the application. Specifically, when the amount of the coal gasification coarse slag remains unchanged, with the increase of the amount of the chitosan solution, the saturated adsorption time (s) and the water loss rate (%) show a trend of first decreasing and then increasing; specifically, when the ratio of m 煤气化粗渣 and m 壳聚糖溶液 is less than 1:50, the saturated adsorption time (s) and the water loss rate (%) show a gradually decreasing trend; when the ratio of m 煤气化粗渣 and m 壳聚糖溶液 is greater than 1:50, the saturated adsorption time (s) and the water loss rate (%) gradually increase.

[0112] When the amount of the coal gasification coarse slag remains unchanged, with the increase of the amount of the chitosan solution, the average saturated adsorption specific gravity (g / g) and the evaporation efficiency (kg·m -2 ·h -1 show a trend of first increasing and then decreasing; specifically, when the ratio of m 煤气化粗渣 and m 壳聚糖溶液 is less than 1:50, it gradually increases; when the ratio is greater than 1:50, it gradually decreases.

[0113] When the amount of the coal gasification coarse slag remains unchanged, with the increase of the amount of the chitosan solution, the absorbance of the aerogel material in the wavelength range of 200-2500 nm continuously decreases, but when the ratio of m 煤气化粗渣 and m 壳聚糖溶液 is less than 1:50, the coal gasification coarse slag cannot be uniformly dispersed in the chitosan solution; when the ratio reaches 1:50, the coal gasification coarse slag can be uniformly suspended.

[0114] In summary, when the ratio of m 煤气化粗渣 and m 壳聚糖溶液 is 1:50, the performance in all aspects can be optimal.

[0115] The application further studies the influence of the concentration of the glutaraldehyde solution in step five of Example 1 on the final product of the application; the research process is as follows.

[0116] The volume fraction of glutaraldehyde solution used in Example 1 was 2%; on the basis of Example 1, the volume fraction of glutaraldehyde solution was changed to 1.5%, 2.5%, respectively; other conditions were unchanged. The performance indicators of the prepared composite aerogel were detected, and the results are shown in Table 7.

[0117] Table 7, Influence of different volume fractions of glutaraldehyde solution on the performance of composite aerogel

[0118] The study shows that different volume fractions of glutaraldehyde solution have an important influence on the performance of the final product of the application. Specifically, as shown in Figure 15 , the products of composite aerogel prepared by using glutaraldehyde solutions with volume fractions of 1.5%, 2.0%, and 2.5% respectively. The study shows that when the volume fraction of glutaraldehyde solution is 1.5%, the material is black, and the structure of the composite aerogel material collapses after freeze-drying Figure 15 a); when the volume fraction of glutaraldehyde solution is 2.0%, as shown in Figure 15 b, the material is black, the morphology is good, and the performance is excellent; when the volume fraction of glutaraldehyde solution is 2.5%, as shown in Figure 15 c, the material is green, the morphology is good, but the performance is not as good as Example 1 with a volume fraction of 2.0%, especially the absorbance is only about 81%, which greatly affects the evaporation efficiency of the composite material, and the evaporation efficiency is only 1.4 kg·m -2 ·h -1 ; in summary, when the volume fraction of glutaraldehyde solution is 2%, the performance in all aspects can be optimal.

[0119] The application calculates the photo-thermal conversion efficiency of the composite aerogel prepared in Examples 1 to 7, as follows.

[0120] The equivalent evaporation enthalpy calculation formula 2 of the composite aerogel is as follows:

[0121] In formula 2, : equivalent evaporation enthalpy of composite aerogel (kJ / kg).

[0122] : evaporation rate of water under 0 sun kJ / (m 2 ·h).

[0123] : evaporation rate of composite aerogel under 0 sun kJ / (m 2 ·h).

[0124] Latent heat of vaporization of water, the value is 2453 kJ / kg.

[0125] The formula 3 for calculating the light-heat conversion efficiency of the composite aerogel is as follows:

[0126] In the formula 3, Light-heat conversion efficiency (%).

[0127] Evaporation rate of the composite aerogel under 1 sun, kJ / (m 2 ·h).

[0128] Evaporation rate of the composite aerogel under 0 sun, kJ / (m 2 ·h).

[0129] Equivalent evaporation enthalpy of the composite aerogel (kJ / kg).

[0130] Light power, the value is 3600 kJ / (m 2 ·h).

[0131] Table 8, summary table of light-heat conversion efficiency of the composite aerogels prepared in examples 1 to 7 of the present application

[0132] At present, the highest light-heat conversion efficiency of the reported interfacial evaporation materials is 90%, and the light-heat conversion efficiency of the composite aerogels prepared in examples 1 to 7 of the present application all reaches 90%, which indicates that the composite aerogels of the present application have excellent light-heat conversion capacity.

[0133] It can be understood that the present application is described through some examples, and those skilled in the art know that various changes or equivalent replacements can be made to these features and examples without departing from the spirit and scope of the present application. In addition, these features and examples can be modified to adapt to specific conditions and materials under the guidance of the present application without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific examples disclosed herein, and all examples falling within the scope of the claims of the present application are within the scope of protection of the present application.

Claims

1. A coal gasification slag-based aerogel porous material, characterized in that, The preparation method comprises: Coal gasification slag pretreatment: grinding, nitric acid soaking modification, water washing and drying of coal gasification slag to obtain pretreated coal gasification slag; The pretreated coal gasification slag is dispersed into a solution of a natural polymer material capable of self-gelation to prepare a dispersion liquid, the natural polymer material containing at least one of carboxyl, hydroxyl and aldehyde groups; the dispersion liquid is subjected to first freeze drying to obtain a solidified material; The solidified material is soaked in a crosslinking agent, washed with water to obtain a crosslinked aerogel; the crosslinked aerogel is fully soaked in a tert-butyl alcohol solution and subjected to second freeze drying to obtain a coal gasification slag-based aerogel porous material.

2. The coal gasification slag-based aerogel porous material according to claim 1, characterized in that, The coal gasification slag is coal gasification coarse slag or coal gasification fine slag; after grinding, the coal gasification slag is sieved through a 50-200 mesh sieve; the nitric acid soaking modification uses a 3-6 mol / L nitric acid solution, the soaking time is 3-6 h, and the soaking temperature is 60-120 ℃; the drying temperature during the coal gasification slag pretreatment process is 60-100 ℃, and the time is 3-5 h.

3. The coal gasification slag-based aerogel porous material according to claim 1, wherein, The natural polymer material capable of self-gelation is chitosan; when prepared, the chitosan is mixed with an acetic acid solution to prepare the solution of the natural polymer material capable of self-gelation.

4. The coal gasification slag-based aerogel porous material according to claim 1, wherein, The natural polymer material capable of self-gelation is any one of pectin and starch, which is mixed with water to prepare the solution of the natural polymer material capable of self-gelation.

5. The coal gasification slag-based aerogel porous material according to claim 1, wherein, The mixing mass ratio of the pretreated coal gasification slag to the solution of the natural polymer material is 1: (10-90).

6. The coal gasification slag-based aerogel porous material according to claim 1, wherein, The first freeze drying of the dispersion liquid is performed under the following conditions: the cold trap temperature is -40 to -60 ℃; the freeze drying time is 48-72 h; and the vacuum degree is 30-100 Pa.

7. The coal gasification slag-based aerogel porous material according to claim 1, wherein, The crosslinking agent is a glutaraldehyde solution, the volume fraction of the crosslinking agent is 1.5-2.5%, the crosslinking agent soaking time is 24-48 h, and then the crosslinking agent is removed by soaking in deionized water until the conductivity of the soaking liquid is 1-10 μS / cm to obtain the crosslinked aerogel; the crosslinked aerogel is fully soaked in a tert-butyl alcohol solution, and then subjected to second freeze drying under the following conditions: the cold trap temperature is -40 to -60 ℃, the freeze drying time is 48-72 h, and the vacuum degree is 30-100 Pa to obtain the coal gasification slag-based aerogel porous material.

8. A coal gasification slag-based aerogel porous material, characterized in that, The preparation method comprises: Coal gasification slag pretreatment: grinding, nitric acid soaking modification, water washing and drying of coal gasification slag to obtain pretreated coal gasification slag; The pretreated coal gasification slag is dispersed into a solution of a natural polymer material capable of self-gelation to prepare a dispersion liquid, the natural polymer material containing at least one of carboxyl, hydroxyl and aldehyde groups; the dispersion liquid is subjected to first freeze drying to obtain a solidified material; The solidified material is soaked in a crosslinking agent, washed with water to obtain a crosslinked aerogel; the crosslinked aerogel is fully soaked in a tert-butyl alcohol solution and subjected to second freeze drying to obtain a coal gasification slag-based aerogel porous material; 9. Use of the coal gasification slag-based aerogel porous material according to claim 1, characterized in that, Used as a soil water-retaining agent or a soil conditioner.

10. Use of the coal gasification slag-based aerogel porous material according to claim 1, characterized in that, Used as an interfacial evaporation material for treating high-salinity wastewater.

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